Attention to the problems posed by natural hazards in West and Central Africa was brought into sharp focus by the deaths of an estimated 1700 people in the valleys to the north of Lake Nyos in 1986. Prior to that the only, well documented, major natural catastrophe was the 1983 earthquake which killed at least 275 people in northwestern Guinea. Though we would not wish to appear to suggest that the 1939 Accra earthquake, which killed 16 people, or the Lake Monoun disaster, which killed 37 people in 1984, were not significant events for the areas concerned. The full horror of the Lake Nyos gas disaster was exacerbated, as far as the outside world was concerned, by initial uncertainty concerning its cause. During the first phase of the investigation there were considerable disagreements between some of the participating groups of scientists. Many of these disagreements have now been resolved and it is to be hoped that the contributions in this volume will further help to resolve some of the outstanding uncertainties. However, although it is important to understand what happened at Lake Nyos in 1986, and why it happened, it is more important for the future of that area that further similar disasters should be avoided. We can only hope that this volume will help to establish a solid foundation for future research into ways of removing excess gas from the lake.

Within the last decade or so, the accelerated growth of Nigeria in the fields of urbanisation, population, business as well as industry has led to some attention in assessment of available water resources in various parts of the country. Many workers (du Preez and Barber, 1965; Jackson, 1978; Faniran and Omorinbola, 1980; Ofodile, 1983; Egboka, 1983; Akujieze, 1984; Ogbukagu, 1984; Uma, 1984) have made significant contributions in this area. Water is important because the attainment of the goals of any society as well as the health and well-being of the population depends on a plentiful and reliable supply of this natural resource. Water forms an indispensable input into economic activities such as commerce, tourism and industry. The results of the various researches have revealed that water resources (surface and groundwater) in many parts of the country, especially the southern part, are more than adequate to meet any demand and only need development. A complete appraisal of available water resources is often best accomplished when aspects of water quality are included. This is because in a planned water supply system, quality constraints and requirements dictate the sources of water allocated to various stages. A public water supply, though contributing greatly to the human health and well-being, can also be a vehicle for spreading disease if not properly handled. In this paper, water quality of selected water resources (surface and groundwater) in some parts of Imo State, Nigeria are reported and suggestions advanced for their healthy untilization.